Method for the transmission of additional information when using a method for compressing data by means of prioritizing pixel transmission

ABSTRACT

The invention relates to a method for the transmission of additional information when using a method for compressing data by means of a prioritizing pixel transmission, said data consisting of individual pixel groups, each of which comprises a positional value within an image array and at least one pixel value. The minimum size of the image array is defined by the height (h) and the width (b) of an image, expressed in pixels. The invention is characterized by the fact that positional values which do not occur in the actual data but lie outside the range of the image array are used during the transmission of additional information.

The invention is directed to a method for transmitting additional information when using a method for compressing data with a prioritizing pixel transmission, according to the preamble of claim 1.

Most information is currently already provided in electronic form. A large number of data formats exist that are optimized and/or specified by a manufacturer for different applications. These data formats are standardized, for example, as so-called MIME types, document formats and graphic formats. Documents can be assembled from documents having different data formats, for example on a website. However, if the individual documents overlap, e.g., if a transparent text is overlaid on a picture, or if a moving display is used, then it may be difficult to find an optimal combination that achieves the highest compression rates, because, for example, the various documents are independent of each other.

A basis of the present invention are methods for compressing and decompressing image or video data through prioritized pixel transmission, are disclosed, for example, in the German-language patent applications DE 101 13 880.6 (corresponds to PCT/DE02/00987) and DE 101 52 612.1 (corresponds to PCT/DE02/00995). These methods process, for example, digital image data or video data consisting of an array of individual pixels, with each pixel having a time-dependent pixel value that describes color and luminance information of the pixel. According to the invention, a priority is associated with each pixel and/or with each pixel group, and the pixels are written to a priority array according to their prioritization. At each point in time, the array includes the pixel values sorted according to their prioritization. These pixels and the pixel value used for computing the prioritization are transmitted and/or stored according to the prioritization. A pixel is given a high priority, if the difference with respect to its adjacent pixels is very large. The actual pixel values are reconstructed on a display. The pixels that have not yet been transmitted are computed from the already transmitted pixel.

The entire contents of the applications DE 101 13 880.6 and DE 101 52 612.1 are included in the present application by reference.

The methods described in DE 101 13 880.6 and DE 101 52 612.1 for prioritizing pixel transmission have a number of advantages, for example a high compression ratio, scalability, error tolerance, etc. In the certain cases, it may be more advantageous to employ a combination of different compression methods. However, it may be a problem to optimally combine these different methods, while maintaining the basis for the compression, namely the prioritizing pixel transmission.

It is an object of the present invention to provide a method for transmitting additional information with the prioritizing pixel transmission that enables an effective compression of documents having a plurality of different document types.

According to the invention, the object is solved by the characterizing features of claim 1.

According to the invention, position values are used when transmitting the additional information that are not included in the actual data, but are located outside the range of the image array.

In an advantageous embodiment of the invention, the additional information is transmitted in the form of textures, which are preferably provided and transmitted in compressed form. The additional information can be provided in any possible compressed format.

With the invention, a significantly higher compression factor is advantageously possible by employing additional information in the form of textures which are transmitted outside the actual image information, but within the same data stream. Transmission of the texture within the data stream obviates the need for opening an additional transmission channel. Conversely, for example, when transmitting Web pages with present technology, a new connection is established for each image. The disclosed in-line data transmission automatically synchronizes the transmission in real-time applications. Transmission of textures also facilitates further processing. Because text within the texture can be transmitted, for example, in ASCII format, there is no longer a need for optical character recognition (OCR) on the receiver side.

Additional embodiments and modifications of the invention are recited in the dependent claims.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 shows a diagram of an image array consisting of 20×21 pixels;

FIG. 2 shows a diagram with different formats of pixel groups;

FIG. 3 shows a newly generated image array with inserted pixel groups in the corner of the image;

FIG. 4 filling in all the areas between the already inserted pixel groups;

FIG. 5 shows insertion of additional pixel groups and filling in the intermediate areas.

An embodiment of the invention will be described below.

The method of prioritizing pixel transmission can advantageously be combined with other (compression) methods when the other methods have one of the following features.

-   -   large area patterns, for example into the form of scalable         vector graphics (SVG)     -   frequently occurring sprites (bitmap pattern)     -   predominantly consisting of text, so that an ASCII transmission         would be advantageous (e.g., newspaper, fax)

The image or video is initially processed at the source in a conventional manner and a prioritizing list of the pixel groups is generated. In parallel, the additional information (e.g., text, pattern) is provided in the original format, optionally compressed.

In the prioritizing transmission, in general, the array position is initially transmitted followed by the values of the respective pixel group. The maximum value of the array position is derived from the height h×width b of the array. Position values located outside the array can be used to transmit additional information. Because there is potentially a large amount of additional information, the type of the additional information has to be described. Existing document formats, for example MIME types, should be used to ensure the largest possible flexibility and compatibility.

The textures are transmitted in the same data stream as the actual image/video data. However, the position value is hereby located outside the normal range of the array.

An allowed position value is, for example: maximal height h×maximum width b+k, wherein k is a predefined value that is known to the transmitter and receiver and that indicates that a texture is included.

When this position value is transmitted, the application in the receiver recognizes that a texture is included.

Instead of transmitting immediately thereafter the values of the pixel groups, a header is initially transmitted that includes the properties of the texture and possibly additional information. The header can include, for example, the following fields:

Document format of the texture

Position of the texture in the image/video array

Size of the texture in the array

Number of bytes required for transmission

Part of the total texture, if the total texture must be subdivided into several parts due to its size

Additional fields for additional use

The actual texture data are transmitted following the header.

The array with the transmitted textures is then reassembled and displayed on the receiver side. 

1. Method for transmitting additional information when using a method for compressing data by way of a prioritizing pixel transmission, wherein the data comprise individual pixel groups, with each pixel group having a position value within an image array and at least one pixel value, wherein the minimal size of the image array is defined by the height h and the width b of an image, expressed in pixels, wherein in the transmission of the additional information position values are used that do not occur in the actual data, but are located instead outside the range of the image array.
 2. Method according to claim 1, wherein the additional information has a position value of height h×width b of the image array+k.
 3. Method according to claim 1, wherein the additional information is transmitted in the form of textures.
 4. Method according to claim 1 wherein the additional information is provided and transmitted in compressed form.
 5. Method according to claim 1, wherein the additional information is identified as being associated with a certain document format.
 6. Method according to claim 1, wherein the additional information comprises a header that includes the properties of the texture and optionally one or more of fields of document format of the texture, position of the texture in the image/video array, size of the texture in the array, number of bytes required for transmission, part of the total texture, if the total texture must be subdivided into several parts due to its size and additional fields for additional use.
 7. Method according to claim 1, wherein priorities are assigned to the additional information depending on its content-related relevance, its temporal relevance or its device-dependent relevance.
 8. Method according to claim 1, wherein the additional information is transmitted in descending order of its priority.
 9. Method according to claim 1, wherein the additional information is recognized in the receiver based on its specific position values. 